The most superior way of asking forgiveness from Allah

 Our prophet Muhammad peace be upon Him said: "The most superior way of asking forgiveness from Allah is: Allahumma anta rabbi la illaha illa anta, khalaqtani wa ana abduka, wa ana ala ahdika wa wa'dika ma-estata'tu, a'auzu beka min sharri ma sana'tu, abu'u laka be ne'mataka alayia wa abu'u laka be-zanbi fa-eghfer lee fa innahu la yaghferu az-zunuoba illa anta".

Its meaning:

 O Allah, you are my Lord, there is none worthy of worship but you. You created me and I am your slave. I keep your covenant, and my pledge to you so far as I am able. I seek refuge in you from the evil of what I have done. I admit to your blessing upon me, and I admit to my misdeeds, forgive me for there is none who may forgive sins but you.

Its reward: 

Our Prophet said: if somebody recites it during the day with firm faith in it, and dies on the same day before the evening, he will be from the people of paradise; and if somebody recites it at the night with firm faith in it, and dies before the morning, he will be from the people of paradise.